• Title/Summary/Keyword: Computational fluid dynamic analysis

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Design Load Case Analysis and Comparison for a 5MW Offwhore Wind Turbine Using FAST, GH Bladed and CFD Method (FAST, GH Bladed 및 CFD기법을 이용한 5MW 해상풍력터빈 시스템 설계하중조건 해석 및 비교)

  • Kim, Ki-Ha;Kim, Dong-Hyun;Kwak, Young-Seob;Kim, Su-Hyun
    • The KSFM Journal of Fluid Machinery
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    • v.18 no.2
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    • pp.14-21
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    • 2015
  • Design lifetime of a wind turbine is required to be at least 20 years. The most important step to ensure the deign is to evaluate the loads on the wind turbine as accurately as possible. In this study, extreme design load of a offshore wind turbine using Garrad Hassan (GH) Bladed and National Renewable Energy Laboratory (NREL) FAST codes are calculated considering structural dynamic loads. These wind turbine aeroelastic analysis codes are high efficiency for the rapid numerical analysis scheme. But, these codes are mainly based on the mathematical and semi-empirical theories such as unsteady blade element momentum (UBEM) theory, generalized dynamic wake (GDW), dynamic inflow model, dynamic stall model, and tower influence model. Thus, advanced CFD-dynamic coupling method is also applied to conduct cross verification with FAST and GH Bladed codes. If the unsteady characteristics of wind condition are strong, such as extreme design wind condition, it is possible to occur the error in analysis results. The NREL 5 MW offshore wind turbine model as a benchmark case is practically considered for the comparison of calculated designed loads. Computational analyses for typical design load conditions such as normal turbulence model (NTM), normal wind profile (NWP), extreme operation gust (EOG), and extreme direction change (EDC) have been conducted and those results are quantitatively compared with each other. It is importantly shown that there are somewhat differences as maximum amount of 18% among numerical tools depending on the design load cases.

FLUID STRUCTURE INTERACTION ANALYSIS OF AUTOMOTIVE REFRIGERANT COMPRESSOR (자동차 냉매 압축기의 FSI(Fluid-Structure Interaction) 해석)

  • Son, I.G.;Pae, S.M.;Kim, K.I.;Yoon, Y.S.
    • 한국전산유체공학회:학술대회논문집
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    • 2010.05a
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    • pp.93-98
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    • 2010
  • One of the most effective key factors to improve performance of automotive reciprocating compressor is the design of suction and discharge reed valves. Reed valves are also the major sources of compressor noise. Valve motion is highly coupled with refrigerant flow. In this study, a process of fluid-structure interaction analysis was developed to predict the cylinder inner flow and the dynamic behavior of valve simultaneously. Interface programs computational structural dynamics code. The full cycle simulations of compressor were performed using FSI analysis was alidated by comparing the simulation results with the experimental results.

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Aeroelastic Response Analysis of 3D Wind Turbine Blade Considering Rotating and Flow Separation Effects (회전과 유동박리효과를 고려한 3차원 풍력발전 터빈 블레이드의 공탄성 응답 해석)

  • Kim, Dong-Hyun;Kim, Yo-Han;Kim, Dong-Man;Kim, Yu-Sung;Hwang, Mi-Hyun
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2009.04a
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    • pp.68-75
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    • 2009
  • In this study, aeroelastic response analyses have been conducted for a 3D wind turbine blade model. Advanced computational analysis system based on computational fluid dynamics(CFD) and computational structural dynamics(CSD) has been developed in order to investigate detailed dynamic responsed of wind turbine blade. Vibration analyses of rotating wind-turbine blade have been conducted using the general nonlinear finite element program, SAMCEF (Ver.6.3). Reynolds-averaged Navier-Stokes (RANS)equations with spalart-allmaras turbulence model are solved for unsteady flow problems of the rotating turbine blade model. A fully implicit time marching scheme based on the Newmark direct integration method is used for computing the coupled aeroelastic governing equations of the 3D turbine blade for fluid-structure interaction (FSI) problems. Detailed dynamic responses and instantaneous Mach contour on the blade surfaces considering flow-separation effects are presented to show the multi-physical phenomenon of the rotating wind-turbine blade model.

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Aeroelastic Analyses of Space Rocket Configuration Considering Viscosity Effects (유동점성효과를 고려한 우주발사체 형상의 천음속 공탄성해석)

  • Kim, Yo-Han;Kim, Dong-Hyun
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2011.10a
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    • pp.64-71
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    • 2011
  • In this study, steady and unsteady aerodynamic analyses of a huge rocket configuration have been conducted in a transonic flow region. The launch vehicle structural response are coupled with the transonic flow state transitions at the nose of the payload fairing. The developed fluid-structure coupled analysis system is applied for aeroelastic computations combining computational structural dynamics(CSD), finite element method(FEM) and computational fluid dynamics(CFD) in the time domain. It can give very accurate and useful engineering data on the structural dynamic design of advanced flight vehicles. For the nonlinear unsteady aerodynamics in high transonic flow region, Navier-Stokes equations using the structured grid system have been applied to the rocket configurations. Also, it is typically shown that the current computation approach can yield realistic and practical results for rocket design and test engineers.

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FLUID-STRUCTURE INTERACTION ANALYSIS FOR VORTEX-INDUCED VIBRATION OF CIRCULAR CYLINDER (유체-구조 연성해석을 통한 원주의 와유기 진동 해석)

  • Kim, S.H.;Ahn, H.T.;Ryue, J.S.;Shin, H.K.;Kwon, O.J.;Seo, H.S.
    • Journal of computational fluids engineering
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    • v.17 no.1
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    • pp.29-35
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    • 2012
  • Fluid-Structure Interaction analysis of a circular cylinder surrounded by incompressible turbulent flow is presented. The fluid flow is modeled by incompressible Navier-Stokes equations in conjunction with large-eddy simulation for turbulent vortical flows. The circular cylinder is modeled as elastic continuum described by elasto-dynamic equation of motion. Finite element method based approach is utilized for unified formulation of fluid-structure interaction analysis. The magnitude and frequency of structural response is analysed in comparison to the driving fluid forces.

Plow Analysis for Radiating Fluid with Density Variation affected by Overheat Ratio (과열비에 따른 유체밀도 변화를 고려한 복사유체 유동 해석)

  • Han C. Y.;Chae J. W.;Park E. S.;Nam M. G.
    • 한국전산유체공학회:학술대회논문집
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    • 2005.04a
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    • pp.75-78
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    • 2005
  • A numerical investigation has been performed to discuss the radiation-affected steady-laminar natural convection in an enclosure under a large temperature difference. Due to inherent nature of this study, the Boussinesq approximation is no longer valid. Therefore the radiating fluid in an enclosure is treated as a ideal gas. To examine the effects of thermal radiation on thermo-fluid dynamic behaviors in complex geometries, two incomplete partitions are introduced. Based on the results of this study, the dispositions of incomplete partitions with radiatively participating medium are found to incur a distinct difference in fluid-dynamic as well as thermal behavior.

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Computational Structural Dynamic Analysis of a Gyrocopter Using CFD Coupled Method (CFD기법을 연계한 자이로콥터의 전산구조동역학 해석)

  • Kim Hyun-Jung;Jung Se-Un;Park Hyo-Keun;Yang Chang-Hak;Kim Dong-Hyun
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.19 no.3 s.73
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    • pp.295-302
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    • 2006
  • In this study, computational structural dynamic analyses of a gyrocopter have been conducted considering unsteady dynamic hub-loads due to rotating blades. 3D CATIA models with detailed mechanical parts we constructed and virtually assembled into the complete aircraft configuration. The dynamic loading generated by rotating blades in the forward flight condition are calculated by a commercial computational fluid dynamics (CFD) code such as FLUENT. Modal based transient and frequency response analyses are used to efficiently investigate vibration characteristics of the gyrocopter. Free vibration analysis results for different fuel and pilot conditions, frequency responses and transient responses for critical flight conditions are also presented in detail.

UNSTEADY FLUID FIELD ANALYSIS OF STAGING SYSTEM (단분리 비정상 유동장의 수치적 해석)

  • Yoon Y. H.;Kwon K. B.;Hong S. K.
    • 한국전산유체공학회:학술대회논문집
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    • 2005.10a
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    • pp.261-267
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    • 2005
  • The unsteady flow analysis of staging system is conducted. This study focuses on comparing the results of two different governing equations between Euler equations and Navier-Stokes equations. The Chimera grid scheme is applied to moving simulations for unsteady flow analysis with dynamic simulation. As a result, it is certified that inviscid simulation have capabilities enough to analyze the present staging problem.

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Nonlinear Characteristics of Flow Separation Induced Vibration at Low-Speed Using Coupled CSD and CFD technique (전산구조진동/전산유체 기법을 연계한 저속 유동박리 유발 비선형 진동특성 연구)

  • Kim, Dong-Hyun;Chang, Tae-Jin;Kwon, Hyuk-Jun;Lee, In
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2002.05a
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    • pp.140-146
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    • 2002
  • The fluid induced vibration (FIV) phenomena of a 2-D.O.F airfoil system have been investigated in low Reynolds number incompressible flow region. Unsteady flows with viscosity are computed using two-dimensional incompressible Navier-stokes code. To validate developed Navier-Stokes code, steady and unsteady flow fields around airfoil are analyzed. The present fluid/structure interaction analysis is based on the most accurate computational approach with computational fluid dynamics (CSD) and computational structural dynamics (CSD) techniques. The highly nonlinear fluid/structure interaction phenomena due to severe flow separations have been analyzed fur the low Reynolds region (R$_{N}$ =500~5000) that has a dominancy of flow viscosity. The effect of R$_{N}$ on the fluid/structure coupled vibration instability of 2-DOF airfoil system is presented and the effect of initial angle of attack on the dynamic instability are also shown.own.

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Flow-Induced Vibration Analysis for Cascades with Stator-Rotor Interaction and Viscosity Effect (스테이터-로터 상호간섭 및 점성효과를 고려한 케스케이드의 유체유발 진동해석)

  • Oh, Se-Won;Kim, Dong-Hyun;Kim, Yu-Sung;Park, Oung
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2006.11a
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    • pp.848-854
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    • 2006
  • In this study, a computational analysis system has been developed in order to investigate flow-induced vibration(FIV) phenomenon for general stator-rotor cascade configurations. Relative movement of the rotor with respect to stator is reflected by modeling independent two computational domains. Fluid domains are modeled using the unstructured grid system with dynamic moving and local deforming methods. Unsteady, Reynolds-averaged Navier-Stokes equations with one equation Spalart-Allmaras and two-equation SST $k-\omega$ turbulence models are solved for unsteady flow problems. A fully implicit time marching scheme based on the Newmark direct integration method is used flow computing the coupled governing equations of the fluid-structure interaction problem. Detailed FIV responses for different flow conditions are presented with respect to time and vibration characteristics are also physically investigated in the time domain.

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